Many wireless networks employ multiple access techniques to provide devices with media access. For example, wireless local area networks (WLANs) defined by the Institute of Electrical and Electronic Engineers (IEEE) 802.11 standards employ a carrier sense multiple access with collision avoidance collision (CSMA/CA) media access technique, which works well with bursty traffic.
In accordance with CSMA/CA, a device wishing to transmit data has to first listen to the communications medium for a predetermined amount of time to determine whether or not another device is transmitting. If the device senses that the communications medium is idle, it may begin transmitting its data. However, if the device senses that another device is transmitting, the device defers its transmission for a randomly determined backoff interval.
Interest in millimeter wave (e.g., 60 Gigahertz) networks is increasing. For example, work is underway to develop an IEEE 802.11 WLAN standard (IEEE 802.11ad) having 60 GHz features. Such networks may make extensive use of beamformed (directional) transmissions. Unfortunately, CSMA/CA does not work well in environments employing directional transmissions. This is because carrier sensing in such environments can be impaired.